Bimanual coordination is important to adaptive human functioning;yet our understanding of its development and relation to developmental disorders is incomplete. This project will adopt a dynamic systems approach to examining bimanual competence in children between the ages of 15 and 27 months, a target group whose activity has previously been under-represented in the literature. The project's methodology will include a longitudinal study of an easily elicited rhythmic percussive behavior, drumming. Individual developmental trajectories will be mapped according to the principles and methods of developmental systems analysis. Additionally, introduction of auditory or human models will allow the investigator to determine whether reducing the self-regulatory requirements placed on the child increases the stability of bilateral rhythmic behavior at different points in the development of this skill. It is hypothesized that such reduction of the self-regulatory requirements will indeed increase stability of the drumming behavior at transitional points at which the behavior shifts from one point to another. Kinematic analysis will allow microgenetic as well as ontogenetic data to be reported at both the individual and aggregate level, in keeping with dynamic systems approaches to analysis. It is believed that this project will inaugurate a productive program of study that will allow in-depth examination of the motoric, cognitive, and contextual factors that contribute to bimanual competence in young children, as well as lead to potential early diagnostic and intervention applications for atypical developmental conditions. Additionally, it will provide research-training opportunities for several students who are under-represented minority women. It is important to understand the developmental pathways typically experienced by children with respect to bimanual skills, particularly during the first years of life. Children in this age range are undergoing rapid growth in skill development, and early childhood represents a critical point for diagnosis of developmental disorders prior to entry into school. Because bimanual competence is so integral to our daily activity as humans, and because investigators have discovered links between atypical bimanual coordination patterns and developmental disorders, it is believed that this project may ultimately lead to useful nonlinguistic early diagnostic and intervention tools for children at risk for developmental disorders.